2 doors 1200 2door sedan / Nearly cert ready

[Bartman]

What are the injector bosses off?

[DJZ]

I think in reality the plenum volume makes little difference unless you are trying to get absolutely the maximum power you can out of it. If you are somewhere between 80 and 200% I think you'll be sweet.

[2 doors]

injector bosses are side feed sr20, so plenty of options on injectors, these types of injectors are in 90% of cars at pick a part, if you read back through my thread you will see what I have done to get them to work.

Cheers DJZ , I guess I was concerned about the amount of volume of air it would take for the turbo to poke out before reaching boost levels, the more volume of air it takes the more lag ?

im basing this on my moderate knowledge of how compressors work lol.

[nick_m]

yeah I agree with DJZ just make it around engine capacity you'll be right.
What Id worry about more is where your intake runners meet the plenum base, You want a nice big radius there, bigger is better, also dont stick them out off the plenum floor like your picture, both will hurt flow
Other than it will be fine

[2 doors]

yeah I agree with DJZ just make it around engine capacity you'll be right.
What Id worry about more is where your intake runners meet the plenum base, You want a nice big radius there, bigger is better, also dont stick them out off the plenum floor like your picture, both will hurt flow
Other than it will be fine

That's what I would have thought too, but what ive been reading is that as air passes along the sides of the plenum, it creates friction causing the air to slow down, where as the air just off the surface is free of the friction and moves faster, therefore if the trumpets are 1/8 of the plenum dia off the bottom, they are actually picking up the faster flowing air, this is especially important pre boost when the engine is working at an N/A capacity before boosting, then when under boost the whole plenum is equally pressurised and will force the air down the runner regardless.

my initial thoughts were to radius the hell out of the plenum floor where the runners meet it, but a lot of information ive read, advise bellmouths set off the floor of the plenum.

you can understand why its causing me grief, my research suggests gains of up to 5-10% power with bellmouths over a radiused floor.

http://horsepowercalculators.net/intake ... old-design" onclick="window.open(this.href);return false;

quite a few of these images show bellmouths just off the floor of the plenum
http://www.google.co.nz/search?q=turbo+ ... 38&bih=660" onclick="window.open(this.href);return false;

bearing in mind this is about trying to keep the airspeed up pre boost.

[jas1200]

Dont mean to ask a silly question but what car will this be going into? If I was you id be wanting to test it/ see how it goes once its finished, but your 2 door 1200 dosnt look like its ready for it.

[2 doors]

Dont mean to ask a silly question but what car will this be going into? If I was you id be wanting to test it/ see how it goes once its finished, but your 2 door 1200 dosnt look like its ready for it.

lol its going in the 2 door, I will want to drive it once the engine is done as you suggest, im just building the engine and bits and pieces while I wait for some space in the garage, the car itself isn't as faraway from completion as you may think, panel and paint is never a problem for me, its the other stuff that seem to take the longest.

[nick_m]

everything changes with boost though Wal. You got to remember you are forcing the air in there. Not trying to suck it through
I would put them flush with the plenum floor
Edit, actually read the whole post you put up. Im not 100% convinced to be honest, I can see where they are coming from but im yet to see a factory boosted motor with anything resembling what is described.
To be honest given the cars power targets and intended use. I reckon go with what ever is easiest to make to the best level. Its easy to start chasing your tail, when in reality if you build it, it will still work perfectly fine (I know I chase my tail a lot)

[2 doors]

everything changes with boost though Wal. You got to remember you are forcing the air in there. Not trying to suck it through
I would put them flush with the plenum floor
Edit, actually read the whole post you put up. Im not 100% convinced to be honest, I can see where they are coming from but im yet to see a factory boosted motor with anything resembling what is described.
To be honest given the cars power targets and intended use. I reckon go with what ever is easiest to make to the best level. Its easy to start chasing your tail, when in reality if you build it, it will still work perfectly fine (I know I chase my tail a lot)

Im guessing factory would never do it this way as the costs would be inhibitive for mass production, seems a fair amount of after market tuning places go down this route though.

speaking of chasing tails, I welded up the top part of the plenum tonight, and when I put it back on the engine, I decided the shape was all wrong, the lines and shape didn't suit the rest of the setup, so its in the bin and ill start again tomorrow night.

will be interesting to see where I end up with this thing, as you say build it and it will work, there are a heap of log type plenums out there that seem to work very well, could be a case of wanting it all, might have to make a compromise........ stay tuned.

[2 doors]

another sunday another progress post,

today I spent a couple of hours scraping the paint from the trans tunnel, I have used a special tool to do the scraping, see if you can spot what it is.